As conventional event detecting apparatuses, there have been well known event detecting apparatuses that sense an intrusion of a person by installing sensors such as infrared beam sensors.
However, information obtained from a sensor is local. Therefore, in order to observe a wide range in these methods, it is necessary to install many sensors or cameras so as to eliminate caution areas or blind spots. Moreover, the sensing capabilities thereof are dependent on the function, the installing place, the number, and the like of each sensor, which leads to an increase in cost in order to improve the sensors performance.
Further, interior intruder sensing by use of UWB-IR (Ultra-wideband Impulse-radio) has been proposed (for example, refer to Non Patent Literature 1). Because this technique uses microwaves, its sensing range is wide. Further, UWB-IR has a wide band, which is excellent in pass-band resolution and permeability in respect to obstacles such as walls. Accordingly, it is possible to sense an intruder by monitoring a variation in a power delay profile with UWB-IR.    [Non Patent Literature 1] Keiji Terasaka and three others, “Study on Indoor Human Body Detection Using UWB-IR,” IEICE Transactions on Communications (Japanese Edition), Jan. 1, 2007, Vol. J90-B, No. 1, pp. 97-100.